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By February 2007, five years after the groundwater was found to be impact-free, construction of the Site Improvement Project was substantially complete;however, the vegetation in the evapotranspirative (ET) cover was not well established. Further work was needed to establish the vegetation. This project also included a barrier between existing Module"I"refuse and new refuse. At the direction of RWQCB staff, the County installed a gas-tight barrier equivalent to a base landfill liner such as is required to place refuse on native soil. In November 2007,the ET area was again reseeded, but growth remained insufficient for adequate ET cover. In November 2008,the closure cap soil was amended and fertilized, and again seeded. In the spring of 2009,vegetation was growing healthily on the ET cap area. On June 10, 2009, CVRWQCB staff issued a notice of violation for discharge of wastes outside of containment due to the presence of VOCs in the soil within County property. Refuse was not discharged at those locations. On March 4, 2009, San Joaquin County staff noticed that the landfill gas (LFG) condensate pump discharge was connected to the secondary leachate sump of Module 1 rather than to the LCRS. In April 2009,the LFG condensate was removed from the secondary sump, and the soil gas trench(installed beneath the liner of Module 1) was activated to enhance the protection of groundwater. An investigation in October 2009 indicated that the condensate had been forced between the primary and secondary liner up the side of the landfill, and had been discharged a few feet below ground surface into the anchor trench along the side of the landfill where the primary and secondary liners terminate. In March 2011,the continuing removal of liquid from the secondary sump, including increased removal during a high-water level event in the primary sump, indicated hydraulic communication between the primary and secondary sump. In October 2011, as agreed by District staff,the County installed automatic pump in the secondary sump to maintain the liquid head above the liner below 12", in accordance with CC Title 27. This pump continues to operate. VOCs were again confirmed in MW-3 in the first quarter 2011, approximately four years after covering portions of Module"P'with HDPE liner material. This was the first VOC detection in this well since fourth quarter 2001. No other well indicates impact. In considering the timeline of detections and corrective actions, a four or five year lag between action and result may be apparent: • Winter of 1995/96 and continuing through three winters: water ponded over refuse near MW-3 • 1998: ponding corrected • March 2001 (five years after the start of ponding): VOCs indicated at MW-3 • February 2002 (four years after ponding was corrected): VOC impact is no longer seen at MW-3 • 2002 to 2006: MW-3 is free of VOCs without a LFG system in operation Foothill Sanitary Landfill 6 Department of Public Works/Solid Waste 1s`Semester 2012 Groundwater Monitoring County of San Joaquin—July 17,2012